The invention discloses a method and device for low-temperature drying of residual activated sludge from sewage treatment. The device comprises sludge freezing equipment, a sludge maintenance chamber, a sludge unfreezing and primary dehydrating device, sludge dehydrating equipment and a sludge airing device; and the residual activated sludge, which is obtained after primary dehydrating treatment is conducted, of a sewage treatment plant is treated by the sludge freezing equipment, the sludge maintenance chamber, the sludge unfreezing and primary dehydrating device, the sludge dehydrating equipment and the sludge airing device sequentially to obtain sludge subjected to low-temperature drying. According to the method and device for low-temperature drying of the residual activated sludge from sewage treatment, through cooperation of the sludge unfreezing and primary dehydrating device, the sludge dehydrating equipment and the sludge airing device, the sludge is continuously dehydrated and aired, a sludge drying cycle is shortened, and a drying effect is obvious. All drying processes are conducted under conditions of normal temperature and temperature lower than the normal temperature, and volatile gas which is generated due to secondary fermentation of microorganisms in the sludge is reduced, so that pollution is reduced. According to the method and device for low-temperature drying of the residual activated sludge from sewage treatment, the sludge is directly frozen, no other chemical agents need to be added, the drying cost is reduced, and meanwhile, the biology characteristics of the sludge remain unchanged, so that a foundation is laid for resource utilization of the sludge.